Hi,
Sorry, I didn't realise that the postSubmit event was added in XFA specification 2.8:
"XFA 2.8 is supported by Acrobat Pro 9.0, Adobe Reader 9.0, LiveCycle Designer ES version 8.2, and LiveCycle ES version 8.2."
The postSubmit event is available in the events dropdown:
It is an ideal event for what you are trying to achieve.
As an alternative you could move your submit script to the mouseUp event (which fires early in the user interaction) and then move the call to your custom reset function to the click event, which fires after the mouseUp.
This separation of the script may be just enough to clear the form after submission.
Good luck,
Niall